[Endoperez]

Raise Skeletons, from Enchantment. You need several D3 (or D2+Skull Staff, but that's expensive) or better casters, but they can spam large enough armies that most armies will just fall down from fatigue against them.

S1D1 mages, like LA Jotunheim's Siethkona, can spam Nether Darts.

Another way, which takes longer to pay off, is via casting Dark Knowledge, summoning Bane Lords and forging Wraith Swords.